Electronic vehicle systems require the compression travel of individual axles or wheels as a measured variable. Among such systems are, in particular, systems for automatic level control in the case of pneumatically suspended vehicles.
Conventional sensor devices convert the compression travel into a rotary motion by means of a lever-type mechanism, and the angle of rotation is measured with the aid of angular-position sensors such as rotary potentiometers. A disadvantage of these systems lies in the often delicate lever-type mechanism, which can be damaged by falling rocks, for instance. Loss of the automatic-level control means a total failure of the vehicle and entails high breakdown costs, in particular if commercially utilized vehicles are involved.
To remedy these disadvantages, the related art therefore also suggests generic contactless sensor devices operating according to the ultrasonic principle. Here, it has shown to be disadvantageous that the measuring accuracy of ultrasonic sensors is heavily dependent upon environmental conditions such as the outside temperature, the ambient pressure, as well as the degree of soiling of the sensor surfaces.